As I posted elsewhere Customer Service at GTS does not recommend the Headlight covers for road use, only for show. They indicated the heat will warp the headlight covers. While they did not say anything about the original headlights I can imagine that with the cover on and no way to dissipate the heat the original headlight lenses may be effected as well.
Here's their email address to check with them directly -
customerservice@teamxenon.com